With the introduction of the O.S. .21XZ-M 3.5cc Inboard Marine Engine and the O.S. .21XM V.II Air-Cooled Outboard Marine Engine, O. S. continues its legacy of marine racing dominance – engineered to take down the competition!

.21XZ-M 3.5cc Inboard Marine Engine

Based on the race-proven 21XZ-R on-road powerhouse and adapted for marine racing with a water-cooled cylinder head